A wirelessly transmitted signal may comprise a transmitted information signal, e.g. data such as phone-conversations, video-phone-conversations, WWW-applications, video and audio applications, file transfer or sharing and any type of digital and/or analogue data, Bluetooth data, traditional radio signals, etc., superimposed on a carrier signal with a high(er) frequency. In order to recover the transmitted information signal, it is today common to use an antenna to receive the wireless signal, a local oscillator generating a high frequency RF signal substantially tuned to the received high frequency carrier signal, a phase comparator for continuous tuning and locking of the high frequency RF signal generated by the local oscillator to the received high frequency carrier signal of the wireless transmitted signal and a high radio-frequency (RF) signal mixer. In the RF mixer, the locally generated high frequency RF signal and the received transmitted information signal superimposed on a high frequency carrier signal are mixed in order to obtain a baseband (low frequency) version of the transmitted information (desired data). This process is referred to as frequency down-conversion. Once the transmitted information signal has been recovered, it may be transmitted further or processed locally, depending on the application of the transmitted signal.
A problem of the prior art is the high costs of the components e.g. the local oscillator generating a high frequency RF signal, the phase comparator and the RF mixer, all functioning at high frequencies (e.g. in the range from 10-60 GHz) used to transmit wirelessly high bandwidth signals.
A further problem of the prior art is that the local oscillator is required to be tuned with substantial accuracy to the frequency of the received carrier signal. Said tuning can be complicated by drift in the carrier signal frequency or temperature changes.
Moreover, the bandwidth of the RF mixer and the frequency of the local oscillator are commonly fixed, e.g. by the manufacturer of the device, in its original design thereby making it difficult to accommodate higher bandwidths at later upgrades of a transmission system.